// let str:string  = 'aaa'

// str = 3

// let arr:number[] = [3, 4, 5]
// let arr:string = 'ddd'

// arr.forEach 

let cust = {
  name: 'zhangsan',
  age: 23
}

cust.age

interface Student {
  name: string,
  age: number
}

let student:Student = {
  name: 'zahngsan',
  age: 25
}

let students = {
  name: 'zahngsan',
  age: 25
}

student.age
students.name